Field of the Invention
The invention relates to a liquid crystal display apparatus, a source driver and a method for controlling polarity of driving signals thereof, and more particularly, relates to a method for controlling polarity of driving signals without adding extra pins on a source driver.
Description of Related Art
In the existing technical field, a polarity sequence for the horizontal two dot (H2DOT) inversion cycles once per every four channels. Referring to FIG. 1A and FIG. 1B, FIG. 1A and FIG. 1B are schematic diagrams illustrating a method for controlling polarities of source driving signals in the conventional technology. In FIG. 1A, source drivers 110 and 120 connected in series with one another receive polarity controlling information POLA and POLB, respectively, so as to control polarities of source driving signals generated by these source drivers. Herein, the polarity controlling information POLA and POLB may be a digital signal having an N-number of bits to thereby control the source drivers 110 and 120 in order to generate various possible polarity sequences for the source driving signals. According to FIG. 1B, in the condition where driving channels provided by the source drivers 110 and 120 are not a multiple of 4, for maintaining the polarities of source driving signal in a variation sequence of +, −, −+ at an intersection area ITZ of the source drivers 110 and 120, a polarity variation generated by the source driver 120 must be different from that of the source driver 110. This results in an issue similar to a polarity discontinuation occurred when starting the horizontal two dot inversion.
Furthermore, as shown in FIG. 1C which illustrates another method for controlling polarities of source driving signal in the conventional technology, in the recent conventional technology, an inversion technique known as the H4 Inversion that cycles once per every eight channels, is commonly used on a RGBW panel in order solve an image flicker phenomenon caused by the same polarity for neutral colors. Accordingly, it is obvious that the polarity discontinuation may also occur when a total of driving channels is not a multiple of 8.
Based on the above description, in a display of the conventional technology, in order to perform the horizontal two dot inversion mechanism and the H4 Inversion mechanism, it is required to dispose extra pins on the source drivers 110 and 120 to receive different polarity controlling information POLA and POLB, respectively. As such, a number of the pins of in a source driver chip may be increased to increase a layout area of the source driver chip which leads to increases in the circuit costs. Also, since extra transmitting lines are also required in order to provide a polarity control signal to the extra pins of the source driver chip, the circuit costs increase accordingly.